The long term objectives of this application are; i) to better understand the basic molecular pathology behind Diamond-Blackfan anemia (DBA), and ii) to develop a novel treatment modality for DBA. The first objective will be achieved using ribosomal protein (RP) S19, its messenger RNA (mRNA) and, its gene. RPS19 is found mutant in 25% of patients with DBA but the mechanisms by which RPS19 acts remain unknown. Specifically, the project aim at the identification of factors interacting with RPS19 and/or its mRNA. In vitro transcribed RPS19 mRNA will be analyzed for its interacting partners in erythroid and myeloid cell lines. A system will also be used to identify and isolate specific RPS19 interacting proteins or RNAs after chemical cross linking in UT-7 and K562 cells. An established system will also be used to study the effect of mutant RPS19 on splicing in erythroid cell lines. Factors interacting with RPS19 or its mRNA may clarify the pathway through which a mutant RPS19 mediates DBA and possibly other bone marrow failure syndromes. Such newly identified pathways may also serve as targets for future therapeutic intervention. For novel treatment modalities, a mouse model for DBA with a disrupted Rps19 gene will be subject to gene transfer. Erythroid precursor cells (Lin-, c-kit+) from the Rps19+/- mice are isolated and transduced with a Rps19-GFP lentiviral construct. Cells expressing Rps19 are re-introduced and the effect on erythroid cell production, Rps19 expression and general health/growth of mice will be monitored in vivo. The project will use an ideal environment and expertise to achieve these objectives. The expected results will help to shed light on mechanisms regulating erythropoiesis as well as to improve the outcome of patients with DBA.